Convertible Senior Notes - Convertible Debt (Details) - USD ($) $ in Thousands	1 Months Ended
	Apr. 30, 2018	Aug. 02, 2020	Jul. 31, 2019
Liability:
Less: debt issuance costs, net of amortization	$ (12,900)
Stockholders' equity recorded at issuance:
Less: debt issuance costs	(12,900)
Convertible Senior Notes
Liability:
Principal		$ 575,000	$ 575,000
Less: debt discount, net of amortization		(78,206)	(91,378)
Less: debt issuance costs, net of amortization	(9,800)	(5,662)	(6,615)
Net carrying amount of the Notes		491,132	477,007
Stockholders' equity recorded at issuance:
Less: debt issuance costs	(9,800)	$ (5,662)	$ (6,615)
Additional Paid-In Capital
Liability:
Less: debt issuance costs, net of amortization	(3,068)
Stockholders' equity recorded at issuance:
Allocated value of the conversion feature	136,333
Less: debt issuance costs	(3,068)
Additional paid-in capital	$ 133,265